The major theme of this program project is expressed in our title. Our ultimate goal is to provide a basic foundation for a rational approach to the management of Menjere's disease and other disorders of inner ear fluids. In order to achieve this goal, the fundamental mechanisms underlying fluid dynamics in the inner must first be elucidated. This research, covered in five subprojects, ranges from basic ion transport mechanisms in inner ear epithelia to clinically relevant studies of the adaptive response to interferences with fluid dynamics of the semicircular canals. Project #1 involves the use of a novel tracer technique to measure directly the flow and volume of endolymph in different parts of the inner ear. Project #2 complements project #1 by examining the chemical factors responsible for generation of hydrops and the temporary beneficial effects of glycerol dehydration. In project #3, the most fundamental cellular mechanisms involved in secretion of K and generation of the endolymphatic potential will be studied in the dark cell region of the utricle. Project #4 is aimed at the elucidation of the chemical nature of the tectorial membrane and analogous superstructures of the vestibular system. In addition to a rigorous characterization of the type(s) of collagen in the tectorial membrane and related structures, the amount and distribution of glycosaminoglycans and glycoproteins will be studied by quantitative analytical and special conventional histological preparations of the tectorial membrane.